The Doc Savage, Shadow, and Spider double novel reprints are now down to $3 apiece on Radio Archives. The latest Radio Archives email newsletter warned that copies of some of them might sell out in the next few days.
EDIT:
Adventure House is also having a sale on Sanctum reprints of Doc Savage, the Shadow, the Spider, the Avenger, the Whisperer, and others. It's a Black Friday sale that's been extended until December 31. Most of the double-novel reprints are priced at $7.77, and the several
superpacks and one
Shadow multi-pack featured there are priced in the $23.97 - $29.97 range. This makes the individual double-novel reprints and some (but not all) of the superpacks a bit higher than Bud's Art books in and of themselves, but Adventure House also currently has a Black Friday free shipping deal, which can actually make your order cheaper than Bud's Art Books in some situations.